1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copier, printer, facsimile machine, or a multifunctional device combining several such functions.
2. Discussion of the Background
In the electrophotographic image forming apparatus market, lowering running costs is a long-felt need. Toward that end, various methods of extending the working life of process cartridges that are used in such apparatuses are disclosed, including use of a removable toner cartridge independently replaceable from an image forming apparatus is disclosed.
In the toner cartridge, toner is delivered from a toner container to a developing unit. In a case in which the toner is delivered using the force of gravity, a complicated member for feeding the toner to the developing unit is not needed in the toner container. Such a gravity-feed configuration has the advantage of being inexpensive, thereby contributing to the lowest running cost. However, a drawback of this arrangement is that a powder pressure of the toner is not controlled because the toner is gravitationally fed from the toner container, and therefore an outlet thereof may be contaminated with the toner when a toner container still containing toner is removed from the image forming apparatus. When the outlet is opened and closed while the powder pressure is high, an opening and closing member of the developing unit is contaminated. Further, because the outlet faces downward, any toner adhering to the outlet tends to scatter and contaminate the surrounding area inside the apparatus.
Therefore, to minimize uncontrolled scattering of the toner adhering to the outlet, typically the outlet is located in a horizontal direction of the toner container so that the outlet does not face downward when the toner container is removed from the apparatus. Alternatively, a toner container having the outlet located at an end in a horizontal direction of the toner container and facing downward without powder pressure is known.
However, conventional toner containers having an outlet in a horizontal direction do not have a power to feed a toner into a developing unit, thus necessitating use of a complicated part such as a feed screw for feeding the toner forward, resulting in a larger and more costly toner container.
In short, a toner container having a downward facing outlet costs less but cannot avoid scattering toner. By contrast, a toner container having an outlet facing in a horizontal direction can avoid scattering the toner but becomes bulky and expensive.